Re: Whizzy New Feature: Paged segmented memory

[Richard B. Johnson]

On Tue, 8 Jan 2002, Anthony DeRobertis wrote:

> 
> On Tuesday, January 8, 2002, at 09:14 AM, Richard B. Johnson wrote:
> 
> > At least with Intel ix8*, even though one can create a discriptor for
> > a (backwards) stack, you would have a hard time using it. 
> > 'Push' op-codes
> > decrement the stack-pointer and 'pop' increments it regardless of
> > the characteristics of the stack-selector.
> 
> You'd have to do it manually, without those instructions. That's 
> what you get for using a CISC architecture from who-knows-when.
> 
> I'd guess most RISC architectures don't have this problem.
> 

Yes, and you can choose any one of a zillion registers to address
your "stack" although there are some de-facto standards, not enforced
by the hardware.  But this all comes with trade-offs discussed from
about all perspectives in the past, context-switches come to mind.
Using Intel, with the proper call-frame on the stack, `iret` switches
context. Setting the proper call-frame and saved register values is
easy because there are so few registers!

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (797.90 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.